1. Field of the Invention
The present invention relates, in general, to linear actuators and, more specifically, for linear actuators for positioning vehicle seat components.
2. Description of the Art
Vehicle seat assemblies are usually provided with a seat adjuster for adjusting the horizontal fore and aft position of an upper track movably mounted in a lower track fixed to the vehicle and, in some cases, with a seat recliner for adjusting the angular position of a pivotal seat back with respect to a seat track assembly mounted on the vehicle floor. One type of seat adjuster includes a plurality of discrete, spaced positions or detents for releasibly locking the upper track to the lower track.
Another type of seat adjuster which is also usable as a seat recliner utilizes a linear actuator formed of a threadingly engaged lead screw and nut to provide an infinite number of user selectible seat adjustment positions. Various means are utilized to releasibly lock the nut in a fixed position to prevent rotation of the nut and the lead screw so as to fix one of the movable components of the seat in a user selected, adjusted position with respect to other components of the vehicle seat. While the latter described type of linear actuator is capable of providing infinite seat adjustment positions, such a linear actuator still lacks a reliable, smooth release operation, particularly when seat adjustment is made under load, i.e. the user's weight on the seat.
Thus, it would be desirable to provide a linear actuator for a vehicle seat which provides a smooth, reliable lock and lock release. It would also be desirable to provide such a linear actuator for a vehicle seat which provides an infinite number of seat adjustment positions. Finally, it would be desirable to provide a linear actuator for a vehicle seat which has a simplified construction, reliable operation, a small overall size and minimal weight.